If you want the best batter life from your Garmin watch either for long activities away from civilization or you just don't want to charge your Garmin too often there are a few steps you can take to have a longer use time between charges.
How to get better battery life from Garmin watches?
My Garmin Forerunner 255 has a great battery life, over 1 week usually with a single charge, and several activities per day. But I do adopt some of the following tips.
Backlight
Depending on the type of display you have this will offer different benefits in term of battery saving. Garmin 255 with a color MIP display is not that affected as an AMOLED but still you can see the benefits.
In System / Display there are 3 settings that you can take advantage off.
During activity, General use and During sleep.
You can set the backlight brightness from 10% to 100%.
Timeout, again depending on the display different values will be available. The MIP display has the option of 4 sec, 8 sec, 15 sec, 30, sec, 1 min, no timeout. The standard 8 seconds seems to be enough during activity and during general use I am fine with 4 sec.
Gestures allows you to set up automatic lighting of the display at any hour or only after sunset.
During sleep I have gestures disabled as I do not want my watch to illuminate my sleep. I will press the light button if I need it.
Watch face
MIP displays (memory in picture) retain the information in each pixel, and update individual pixels as needed. So if you use a simple watch face with not much changing data you will have the best out of the display. My current watch face only displays the day and date, time (no seconds) steps and barometric pressure.
Also having less information on the display means that less sensors are used all the time and this will consume less energy.
You can choose any watch face from the connect app, but the standard watch faces on the watch will probably offer the best optimization regarding battery.
Sensors
Pulse Ox takes quite some power out of the watch, so having it on all day all night will drain the battery much quicker. You can set it to record the oxygen blood saturation all day, during the day, during the night, or on request. On request is the best if you want best battery life out of your watch. And I don't find very useful to have it running all day an night. Especially if you are not training at 5000 meter altitude
Connectivity
If you are in a pinch you can stop the Bluetooth on the watch, I get around 2 extra days just by not having my watch connected to the phone all the time. If you don't care for getting notifications then you can keep it off for the most part of the day. Don't worry, your activities are safe, and will get synchronized with your phone once you activate the Bluetooth.
Battery saver
Satellites
Garmin Forerunner 255 has a few options for which satellites it uses when it tracks activities. As standard Auto is selected, but you can change it in Settings / Satellites.
Off if you don't want tracking and you really want to conserve the battery.
GPS only which offers good battery life, with ok accuracy
All Systems uses all available satellites which offers better accuracy, with decent battery life
All + Multi Band is the best for accuracy, but not as good for battery life
Ultra Trac, best battery but not very good accuracy
Power modes on some Garmin watch models
Pause/Resume later activity
Last tip is for long activities that stretch over hours and you take a brake. Let's say you go riding your bike and stop for a coffee and donuts. You can pause the activity, but the watch will continue to be connected to the satellites and all the sensors. So for better battery life it is better to select Pause / resume later. The activity will be saved and will resume when you start it again (it doesn't create 2 different activities)
